1. Field of the Invention
The invention relates to an optical disc player having a focus pull-in function.
2. Description of Related Art
Nowadays, a multilayer optical disc is known as a type of optical recording medium, in which a plurality of recording layers for recording information data are provided in a single disc. For example, two recording layers separated by a spacer layer forming a relatively small gap are provided in a two-layer DVD (Digital Versatile Disc). Upon recording or reproduction to/from the double-layer optical disc, a laser beam is condensed onto one of the two recording layers and the recording or reproduction of information data is executed to the recording layer. In the recording or reproducing operation, there is a case where a focal position of the laser beam is changed from one recording layer to the other recording layer. The operation such that the focal position of the laser beam is changed to the other recording layer as mentioned above is generally called “focus jump”. Upon focus jump, first, an objective lens is forcedly moved to a position near the optical disc and pulled into a capture range of a focusing servo loop and, subsequently, the focusing servo loop is set to a closed state. Also in a single-layer optical disc having one recording layer, at the time of the initial operation, what is called “focus pull-in” is executed such that the objective lens is forcedly moved to a position near the surface of the optical disc and pulled into a capture range of a focusing servo loop and, subsequently, the focusing servo loop is set to a closed state.
However, if the surface oscillation of the optical disc is large in the state that the servo loop is closed, an inconvenience can occur such that a speed of approaching to the disc surface when viewed from the objective lens becomes excessively high, so that the focus pull-in fails, and the objective lens comes into contact with the optical disc, or the like.